NACWA Letter to M. Hale 

June 2, 2009 

Page 1 

EXECUTIVE COMMITTEE

PRESIDENT

Marian A. Orfeo

Director of Planning 

& Coordination

Massachusetts Water 

Resources Authority

Boston, MA

VICE PRESIDENT

Kevin L. Shafer

Executive Director

Milwaukee Metropolitan 

Sewerage District

Milwaukee, WI 

TREASURER

Jeff Theerman

Executive Director

Metropolitan St. Louis

Sewer District

Saint Louis, MO

SECRETARY

David R. Williams

Director of Wastewater

East Bay Municipal 

Utility District

Oakland, CA

PAST PRESIDENT

Christopher M. Westhoff

Assistant City Attorney 

Public Works General Counsel

City of Los Angeles

Los Angeles, CA

EXECUTIVE DIRECTOR

Ken Kirk

June 2, 2009 

Matt Hale 

Director, Office of Resource Conservation and Recovery 

U.S. Environmental Protection Agency, Ariel Rios Building 

1200 Pennsylvania Avenue, N. W. Mail Code: Mail Code: 5301P 

Washington, DC 20460 

Via Electronic Mail: hale.matt@epa.gov 

Dear Matt, 

Thank you again for taking time to meet with NACWA to discuss your office’s efforts 

to develop a definition of solid waste for Clean Air Act regulatory purposes. As we 

outlined during the meeting and in our February 2 comments, we believe the 

regulatory status of sewage sludge (biosolids) is clear – it is expressly exempted by the 

RCRA statutory definition of solid waste as ‘solid and dissolved materials in 

domestic sewage.’ Congress considered the potential overlap in authority over 

biosolids and chose to comprehensively regulate biosolids under the Clean Water 

Act. EPA’s many rulemakings regarding the definition of solid waste have 

consistently recognized this Congressional mandate.

NACWA understands that the EPA Office of Air and Radiation is developing 

regulations for solid waste incineration units under Section 129 of the Clean Air Act. 

By clarifying that sewage sludge is excluded from the definition of “solid waste” by 

the domestic sewage exclusion, EPA is acknowledging that it must regulate sewage 

sludge incinerators (SSIs) under Section 112 instead of Section 129. This will help 

ensure that incineration remains one of the five available options for biosolids 

management. 

For many years, NACWA has been supporting EPA’s efforts to develop SSI 

regulations under Section 112 of the Clean Air Act. NACWA helped EPA update its 

database so that it included the significant emission reductions achieved by the Part 

503 regulations of SSIs under the Clean Water Act. We have attached a description of 

the data provided by NACWA in response to EPA’s initial estimates of the SSI 

contribution of certain compounds in urban areas regulated under Section 112(k). It 

is our understanding that these corrections and updates resulted in EPA concluding 

that SSIs were not major sources of hazardous air pollutants and that they provided a 

far smaller percent contribution than originally estimated by EPA. 
NACWA Letter to M. Hale 

June 2, 2009 

Page 2 

As area sources regulated under Section 112(k) of the Clean Air Act, NACWA members can be allies in EPA’s 

effort to address risks in urban areas. NACWA members have unique authorities under the Clean Water Act to 

regulate the discharges of non-domestic users of the sewer system. POTW indirect discharge permits can be 

used to reduce the concentration of compounds of concern in the sewage sludge and reduce the amount of

these compounds that may be emitted into the urban environment. On the other hand, the unpredictable 

nature of the domestic sewage contribution would make it virtually impossible for a POTW to simultaneously 

meet all of the established MACT limits for emissions regulated under Section 129. 

We believe that the best way to ensure SSIs are properly regulated under Section 112 is to include in the 

regulatory definition of solid waste now under development an express exclusion for domestic sewage and the 

sludge generated from the processing of domestic sewage. NACWA believes that the scope of the exclusion is 

clear and the existing Part 503 regulations supplemented with targeted reductions under Section 112(k) provide 

a sound basis for comprehensive biosolids regulation. 

Again, thank you and your staff for meeting with us. Please do not hesitate to contact me if you need additional 

information about SSIs or would like to discuss the issue further. 

Sincerely, 

Chris Hornback 

Senior Director, Regulatory Affairs 

ATTACHMENT 

cc: Robert Dominak, Northeast Ohio Regional Sewer District 

 Robert Wayland, USEPA 

 Rick Stevens, USEPA